Summary Our long range goal is to develop an image-guided workstation that uses a novel Continuum Dexterous Manipulator (CDM) and tools to enable next generation of minimally- and less-invasive procedures allowing access to regions not currently accessible with conventional surgical tools in orthopaedic surgery. The system and devices will enable treatment of bone defects such as femoroacetabular impingement, metastatic bone disease, severe osteoporosis in areas including the pelvis/acetabulum, femoral neck, peri- and sub- trochanteric regions, as well as the shin and foot, and finally traumatic fracture repair. The near-term focus of this application is the core decompression for the treatment of Avascular Necrosis (AVN) of the femoral head and reduction of pelvis fracture. We propose the development of an image-guided prototype robot-assisted surgical system for planning, real-time intraoperative monitoring, navigation, and updating of the plans. In the United States, avascular necrosis (AVN, also known as osteonecrosis) of the femoral head occurs in 10000-20000 of patients per year between the ages of 20-50 years old. The incidence of the AVN is even higher in Middle Eastern and Asian countries. AVN occurs due to the loss of blood supply to the bone, leading to the spontaneous death of the trabecular bone, which in turn may cause microfractures in the trabecular bone. Depending on the amount of femoral head involved, collapse of the articular surface will occur as the disease advances. Once collapse of the femoral head occurs in these patients, the disease course rarely regresses. Total Hip Arthroplasty (THA) will be the primary surgery of choice and will provide pain relief to those AVN patients. However, because of the young age of the AVN patients, THA is not the most desirable choice. Core decompression is a conventional techniques used for the treatment of the AVN prior to the collapse of the femoral head. Typically in core decompression the lesion area (death bone) is removed by drilling and debriding. After debriding the bone graft will be inserted and/or bioresorbable material such as calcium phosphates will be injected into the core to fill the void and provide stability. The long-term success of core decompression is dependent on many parameters that may be out of the control of surgeons given the existing tools and techniques. Some of the issues that the current conventional techniques for core decompression does not answer are: 1) complete debriding of the death bone requires significant increase in dexterity of the debriding tools, currently not available to the surgeons; 2) While it is ideal to completely remove the death bone, the extent of the bone removal may be limited by the stability requirements of the femoral head to prevent its collapse underweight bearing conditions. Biomechanical analysis of the stability of the structure, therefore, must be important part of the planning. Further, the successful implementation of the plan will require robot-assisted, image-guided navigation technology that, to our knowledge, is currently not available to the surgeons. To our knowledge, tools for biomechanical planning to maintain the stability of the hip after the surgery and robotic platforms for minimally-invasive treatment of osteonecrosis are not developed. In particular, the design of the manipulators for the full debriding of the AVN poses unique challenges because of the opposing requirements for structural strength and flexibility. We propose to develop and test a prototype robot-assisted surgical workstation for minimally-invasive treatment of the AVN. The workstation, during the planning phase, will highlight the site of the lesion in MRI images of the patient and create an optimized surgical plan. During the procedure, the surgeon will use a Continuum dexterous manipulator (CDM) in conjunction with a positioning robot and various tools to remove the death bone and perform structural augmentation. Our goal is to demonstrate that the proposed system can significantly improve the treatment of the AVN and the stability of the hip, therefore, reducing the need for multiple follow-up surgeries and/or THA surgeries at early ages.